Signalling

Question 1

Examples of signalling using receptor-linked kinases

Answer 1

-Immune system (cytokines)
-Development pathways (growth hormone)
-Insulin

Question 2

Examples of signalling using G-protein coupled receptors

Answer 2

-Rhodopsin (light)
-Adrenaline

Question 3

Examples of signalling via direction diffusion of hydrophobic ligands across membrane

Answer 3

-Steroids (testosterone, oestrogen)
-VitaminD
-Thyroxine
-Retinoic acid

Question 4

Examples of signalling using ion channels

Answer 4

-Nicotinic acetylcholine (ligand gated)
-Ca2+ channels (voltage-gated) -muscle contraction, egg fertilisation, neurotransmitter release, secondary messengers
-Na+ channels (voltage-gated)
-K+ channels (voltage-gated or pH-gated)

Question 5

What do adaptor proteins do?

In receptor-linked kinase signalling

Answer 5

Bind to phosphorylated kinase and pass information onto more general signalling pathway
eg. Grb2 binds to phosphorylated tyrosine residues
Sos then binds to Grb2, causing its GEF domain to be brought to the cell surface and activate the G-protein Ras
G-protein acitvates Raf, triggering a kinase cascade